Lesson 6: Chart Work

-The rules for extracting and plotting a position are simple. Here they are:

- To find the latitude of a position: Use the vertical margins (scale), left or right. They are marked in units of degrees, minutes, and tenths of a minute, and sometimes in seconds (6 seconds = 1/10th of a minute).

- To find longitude of a position: Use the horizontal margins, top or bottom. They are also marked in degrees, minutes, and tenths of a minute, and sometimes in seconds.


Learning Exercise: Finding Latitude and Longitude


Extract from the Chart 12221 TR the latitude and longitude of the lights listed below (use the supplied Light List for general location only).

Cape Charles Light (LL 345)

- Latitude _________________

- Longitude_________________

Wolf Trap Light (LL 6800)

- Latitude _________________

- Longitude_________________

York River Entrance Channel Lighted Gong Buoy “2” (LL 12130)

- Latitude _________________

- Longitude_________________

Chesapeake Light (LL 355)

- Latitude _________________

- Longitude_________________

Rudee Inlet Lighted Whistle Buoy “RI” (LL 425)

- Latitude _________________

- Longitude_________________


Answers:

1. LAT 37 º 07.4’ N LON 075 º 54.4’ W
2. LAT 37 º 23.4’ N LON 076 º 11.4’ W
3. LAT 37 º 07.4’ N LON 076 º 09.2’ W
4. LAT 36 º 54.3’ N LON 075 º 42.8’ W
5. LAT 36 º 50.0’ N LON 075 º 56.8’ W



Learning Exercise: Plotting Latitude and Longitude

Plot the following positions on the chart and identify the following lights-buoys.


LAT 37º 20.2’ N LON 076º 15.1’ W

- Object at above position:_______________________________


LAT 37º 17.8’ N LON 076º 15.7’ W

- Object at above position:_______________________________


LAT 37º 00.1’ N LON 076º 17.9’ W

- Object at above position:_______________________________


LAT 36º 55.6’ N LON 76º 00.4’ W

- Object at above position:_______________________________


LAT 37º 21.8’ N LON 075º 43.7’ W

- Object at above position:_______________________________




Answers:
1. Horn Harbor Entrance Light “HH”
2. New Point Comfort Spit Light “2”
3. Thimble Shoal Lighted Buoy “22”
4. Cape Henry Light
5. Great Machipongo Light “5”